Floor plate-derived dopamine neurons from hESCs efficiently engraft in animal models of PD

SUMMARY

Human pluripotent stem cells (hPSCs) are a promising source of cells for applications in regenerative medicine. Directed differentiation of hPSCs into specialized cells such as spinal motoneurons ¹ or midbrain dopamine (DA) neurons ² has been achieved. However, the effective use of hPSCs for cell therapy has lagged behind. While mouse PSC-derived DA neurons have shown efficacy in models of Parkinson’s disease (PD) ^{3, 4} , DA neurons from human PSCs generally display poor in vivo performance ⁵ . There are also considerable safety concerns for hPSCs related to their potential for teratoma formation or neural overgrowth ^{6, 7}

Here we present a novel floor plate-based strategy for the derivation of human DA neurons that efficiently engraft in vivo, suggesting that past failures were due to incomplete specification rather than a specific vulnerability of the cells. Midbrain floor plate precursors are derived from hPSCs in 11 days following exposure to small molecule activators of sonic hedgehog (SHH) and canonical WNT signaling. Engraftable midbrain DA neurons are obtained by day 25 and can be maintained in vitro for several months. Extensive molecular profiling, biochemical and electrophysiological data define developmental progression and confirm identity of hPSC-derived midbrain DA neurons. In vivo survival and function is demonstrated in PD models using three host species. Long-term engraftment in 6-OHDA-lesioned mice and rats demonstrates robust survival of midbrain DA neurons, complete restoration of amphetamine-induced rotation behavior and improvements in tests of forelimb use and akinesia. Finally, scalability is demonstrated by transplantation into Parkinsonian monkeys. Excellent DA neuron survival, function and lack of neural overgrowth in the three animal models indicate promise for the development of cell based therapies in PD.